The gonadotropic hormones, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), are contained within the same cells and often respond to the same signals, yet under many circumstances they are not secreted in concert. Understanding the mechanisms for independent secretion of LH and FSH at the cellular level is the subject of this proposal. Two hormonal factors that contribute to differential regulation will be studied. They are the gonadotropins themselves, which may exert ultra-short-loop feedback effects upon their own secretion to differing degrees; and the glucocorticoids, which differentially affect gonadotropins by mechanisms that are not understood. Ultra-short-loop feedback could account for independent secretion of LH and FSH under a number of circumstances. It also is a central issue in interpreting results from any static cell culture. Study of glucocorticoids will provide a tool for investigation of differential regulation of the gonadotropins, and it will also yield important information regarding the role of stress and adrenal steroids in suppressing normal hypophysial function. These hormonal factors will be studied using enzymatically dispersed pituitary cells in vitro. The cellular responses of the gonadotrophs will also be studied by observing secretion of LH, FSH, or both from single cells. These observations will be accomplished by labeling secretory cells with specific antibody-conjugated fluorescent microspheres. To enhance the sensitivity and specificity of the microspheres, monoclonal antibodies against rFSH will be developed. These experiments will provide important information regarding differential secretion of the gonadotropins. They will also be of general interest to cell biologists and physiologists studying secretion of proteins from cells with multiple secretory functions.